These attempts to reject environmental variation rest on several grounds.
And greener (in the environmental way, not the color way).
Such cases show in the plainest way the co-operation of external or environmental and internal or constitutional factors.
Tiedemann, 2 the Heidelberg anatomist, who has been generally ignored, although he surpassed many a recent zoogeographer by the wide view he took of the problem; in fact he was the first to connect distribution with environmental or bionomic factors; e.g.
In other words, a balance appears to be always sustained between the internal (hereditary and ontogenetic) and the external (environmental and selectional) factors of evolution.